Flexure of a thin diaphragm as a result of a difference in pressure applied to the two sides of the diaphragm is the basis for some existing pressure transducers. In some versions, the magnitude of the flexure is sensed by a strain gauge network attached to the diaphragm. In another version, the flexure is detected as a change in the capacitance between one side of the (electrically-conductive) diaphragm surface and some conductive portion of the surface of an adjacent fixed electrode. With the existing state of the art for metal diaphragm versions of capacitance diaphragm pressure gauges, pressure differences as small as 1×10−7 Torr can be detected and measured. Thus, except for pressures below about 1×10−7 Torr, pressure measurement tasks in the semiconductor processing industry can be accomplished with capacitance diaphragm pressure gauges. This capability includes the ability of the capacitance diaphragm pressure gauge to perform a switching action when the measured pressure exceeds or falls below a preset value.
On the other hand, if a switching function is all that is required, a capacitance diaphragm pressure gauge is an expensive solution. Also, if several such independently functioning switches are needed on the same semiconductor processing tool in which space is very limited, there just may not be enough space available. Thus, from the standpoint of both cost and size, a compact, relatively inexpensive pressure actuated switch which can operate at a settable pressure anywhere in the range 1×10−6 Torr and above would be advantageous to the semiconductor processing industry. Accordingly, there is a need in the art for such a pressure sensing device that overcomes these deficiencies in the art.